If an application was developed using SCCP-based Cisco IP Communicator endpoints, would that application continue to work for SIP Cisco IP Communicator endpoints? Will the events come in the same order?

Finesse reads in the events in the order that CCE/CCX sends to the Finesse server. So, if the events coming to Finesse is in a different order/with different data, then it is possible that the data in the Finesse notification can be different depending on SIP or SCCP. Basically, there are no guarantees that the notifications will be exactly the same between the two types. But, for Finesse, all dialog notifications follow the same format, so if your integration code just expects a dialog notification, it will get one, but maybe just different values in the tags. If your application is written correctly where it blindly processes the dialog notifications, then the application should work no matter what endpoint is being used.